Improve structure

Improve structure

- Use getopt_long_only() to implement option parsing. This probably
  makes use of small C libraries harder, but that wasn't very much
  possible to begin with, anyway.
- Deprecate bs= and timeout= options in favour of new --block-size and
  --timeout options.
- Compartmentalize a bit more. Yes, the compiler will optimize that away
  in some cases, but what do I care, I don't need to write assembler
  code.

Documentation update to follow.